1. Field of the Invention
This invention relates to a method of inferring measurement specifications used in measuring the properties of electronic circuits such as semiconductor integrated circuits (hereinafter referred to as "IC(s)") by means of a measurement apparatus or the like.
2. Description of the Related Art
In general, after electronic circuits which are represented by IC's have been designed and manufactured, their properties are measured and tested by means of a measurement apparatus of the type which is called a general-purpose IC testing system. This type of measurement apparatus is generally equipped with a plurality of components such as signal generators and measuring devices, and is designed to activate these components in accordance with predetermined measurement programs, thereby enabling performance of various measurements and tests.
FIG. 6 is a block diagram schematically showing the overall arrangement used for measuring the properties of electronic circuits by means of such a measurement apparatus. A measurement apparatus 1 is connected to a measurement jig 3 by a connection cable 2. The measurement jig 3 includes an interface circuit 4 connected to the connection cable 2, a testing peripheral circuit 5, and a socket jig 6, and an IC 7 which is an object to be tested is connected to the socket jig 6. The testing peripheral circuit 5 includes a multiplicity of change-over switches (relays) so as to create peripheral conditions under which the IC 7 is actually used and to enable testing of the IC 7.
The measurement apparatus 1 is activated in accordance with a particular measurement program to input an electrical signal to the IC 7 through the interface circuit 4 and the testing peripheral circuit 5, thereby activating the IC 7. The output of the IC 7 is transferred to the measurement apparatus 1 through the testing peripheral circuit 5 and the interface circuit 4, and measured by the measurement apparatus 1. In this way, various tests on the IC 7 are performed on the basis of the particular measurement program.
The measurement jig 3 and the measurement program used for activating the measurement apparatus 1 are exclusively provided for the circuit design of the IC 7 to be tested, and have heretofore been prepared in accordance with the following procedure:
Step 1: Measurement items are selected on the basis of the device specifications prepared during designing of the IC 7 to prepare a measurement standard for the IC 7.
Step 2: An actual measurement method is examined.
Step 3: A measurement apparatus for use in measurement is selected on the basis of the result of the examination of Step 2.
Step 4: The testing peripheral circuit 5 and the interface circuit 4, both of which are required to make measurement as to all the measurement items of the IC 7 by using the measurement apparatus selected, are designed and the corresponding measurement specifications are prepared.
Step 5: The testing peripheral circuit 5 and the interface circuit 4 are produced, and they are connected to each other with the socket jig 6 connected to the testing peripheral circuit 5, thus preparing the measurement jig 3.
Step 6: A measurement program based on a language form used exclusively for the measurement apparatus 1 is prepared on the basis of the measurement specifications prepared in Step 4.
Step 7: The measurement jig 3 is connected to the measurement apparatus 1 by the connection cable 2, and the IC 7 is connected to the socket jig 6. The measurement apparatus 1 is activated in accordance with the measurement program in order to check whether the IC 7 is set under desired measurement conditions, and thus the output of the IC 7 is measured by the measurement apparatus 1.
Step 8: It is examined whether the measurement jig 3 and the measurement program need to be corrected by comparing the measurement data obtained in Step 7 with predetermined values.
Step 9: If it is determined from the examination of Step 8 that such a correction is needed, the measurement jig 3 and the measurement program are corrected.
In general, the operations of Steps 7-9 are called debugging, and the debugging is performed for each measurement item.
Step 10: After debugging as to all the measurement items has been completed, a plurality of IC's 7 are measured, and the correlations between the resultant measurement data and predetermined data as well as the stability and reproducibility of the result of the measurement are checked. Thus, standard values and the like for use in determining whether the quality of the IC 7 is acceptable are selected on the basis of the result of the confirmation.
Step 11: The measurement apparatus 1 is actually used to make measurements of the properties of the IC 7.
The properties of the IC 7 have heretofore been measured by the method including the above-described steps. In such a method, if the measurement jig 3 and the measurement program are corrected in Steps 7-9, the measurement specifications prepared in Step 4 must be corrected correspondingly. However, in order to check whether the measurement jig 3 and the measurement program correctly reflect the measurement specifications, a knowledge of both hardware and software of the measurement apparatus 1 is necessary and the checking requires a great deal of time. Furthermore, the conventional method has the problem that the qualities of the measurement specifications and the measurement program significantly depends upon differences among individual engineers in charge of debugging. In addition, the above method involves the problem that it is extremely difficult for any engineer other than a staff engineer in charge of debugging to check the measurement specifications.